using System.Drawing;
using static System.Console;
using System.Collections.Generic;
using System.Linq;
class Program
{
    const int num = 1; // 常量不允许 加 static
    struct Point
    {
        public int x;
        public int y;
    }
    static void Main()
    {
        WriteLine("Hello World!");
        WriteLine($"num is {num}");

        List<Point> points = new List<Point> { new Point { x = 1, y = 1 }, new Point { x = 1, y = 2 }, new Point { x = 1, y = 3 } };
        string pointsStr = string.Join(", ", points.Select(p => $"x: {p.x}    y: {p.y}"));
        WriteLine(pointsStr);
    }
}

// 源文件运行 C# 命令行编译器(csc.exe)
// csc HelloWorld.cs